With more than a full year past since China eased restrictions and let COVID-19 sweep its households, scientists are worried a unique opportunity may be slipping away to study long COVID from possibly hundreds of millions of infections in that country.
Global disease experts say little is known about China's experience with long-term COVID effects, which in Britain, Canada, the U.S. and elsewhere are thought to have afflicted millions with debilitating fatigue, brain fog and other symptoms that persist for months or even years.
China's rare circumstances - relying on home-grown vaccines and mostly avoiding COVID until late in the pandemic - could, these experts say, provide particularly valuable data and insights on long COVID.
